I was recently asked whether the product shown below works. TornadoAlert uses lightning patterns to attempt to warn of tornadoes in your local area in time to take shelter. First, I have zero direct knowledge about this product. I do  know that lightning-based tornado detection devices have been around for about 70 years. I saved up and purchased a Sferics  a couple of years after the F-5 Ruskin Heights Tornado (1957) passed south of my neighborhood.  When lightning rates reached a certain point it would display danger (right) and sound a piercing siren.  Today's lightning detectors are more sophisticated and likely to do much better. Here are reviews at Amazon . You will also find a first-hand review at StormTrack .  The science shows that most supercell thunderstorms have a lightning polarity flip (often negative to positive) just before they produce a tornado. For example, this was true of the F-5 tornado that struck Greensburg, Kansas, in 2007. But, it is n...